Electric heating element



R. BARGEHR ELECTRIC HEATING ELEMENT m m m Filed Sept. 4, 1955 INVENTOR.

May 2z, 1956 United States Patent AO ELECTRIC HEATING ELEMENT Robert Bargehr, Lauterach, Vorarlberg, Austria Application September 4, 1953, Serial No. 378,608

Claims priority, application Austria September 8, 1952 Claims. (Cl. 219-19) This invention relates to electric heating elements such as used in heaters, pots for cooking, flat-irons or the like the heating element of which being positioned in an insulating body which is open on its top. The purpose of such arrangement is to utilize the heat of the resistance wiring radiated to the surface to be heated, else the said radiation of heat would be retained by the Walls of the insulating body. By these means economy of electric current and decreasing of the starting period is reached.

An object of my invention is to further improve the ellciency of the heating element. I attain my object by providing an upwards enlarged continuous slot on the top of the beads forming the insulating body. It is advantageous to provide concave reflectors beneath each of the rows of beads causing the heat to be reflected through the slot to the heating plate. Furthermore it is advantageous to shape the slots such as to make the width of the bottom of the same narrower than the diameter of the heating spiral, so that the beads may be threaded to the heating spiral in the usual way. Therefore they are prevented from dropping or from contacting the surface to be heated in case of warping of the resistance wiring when working.

There may be used various embodiments of the reilector. For instance l provide a common rellector for all the rows of beads, the said rellector being undulated in accordance with the said rows, or such undulated body is positioned beneath the rows of beads and is supplied with a rellecting coating facing the said rows of beads. Another embodiment consists in providing individual reilectors connected to the beads respectively. Such individual reilectors may also be performed in different ways.

The invention is illustrated by way of examples in the accompanying drawing in which:

Fig. 1 is a plan View partly in section on the lines I-I and I-l in Fig. 3 showing an electric heating plate with a heating element according to the invention,

F Fig. 2 is a longitudinal section on the line II-II in Fig. 3 is a radial section of the heating plate according to the first embodiment, and

Figs. 4, 5 and 6 show radial sections according to other embodiments.

In each of the embodiments there is a closed heater comprising a heating plate 1 having spiral ribs 2 on the under surface between which ribs the resistance wiring 3 is to be positioned. To the said resistance wiring 3 which is of the usual coiled form there are threaded insulating beads 4, on the top of which upwards enlarging slots 5 are provided, the width of the bottom of the slots being narrower than the diameter of the wiring 3. The sidevfaces of the insulating beads 4 are llattened, such being -conveniently held between the ribs 2 and being prevented 'from turning, but the insulating beads 4 may also be of cylindrical shape. They may be cemented to the ribs 2 :as shown at 6.

According to Fig. 3 a plate 7 is arranged beneath the row of beads the said plate being made of a bad heat conductor and is supporting a rellector 8 which has an undulating groove under each of the rows of beads respectively. In order to obtain a convenient rellection of the heat through the slot 5 the centre of curavture of the undulations may be positioned above the axis of the wiring 3. The reflectors may be cemented to the plate 7 at 1li, its lateral portions 9 are bent against the heating plate.

The embodiment as shown in Fig. 4 dilers from that of Fig. 3 only by replacing the plate 7 by an insulating body 11 which likewise is undulated according to the curvature of the insulating beads and is provided with a metal coating 12 supplied to the body by spraying. 17 is the central screw which serves also for holding the rellector.

According to the Figs. 5 and 6 each insulating bead supports an individual rellector. For this purpose each bead in Fig. 5 is provided with lateral ribs 13 onto which is slid a through-shaped insulating body 14 which is cemented to the ribs 13 at 15. Prior to slide on the bodies 14, reflectors 15 are inserted into the hollow spaces of the same and may be cemented to them at 1l). In this embodiment the resistance wiring 3 is llattened.

According to Fig. 6 each insulating bead is provided with a hollow body 18 having an opening on its front only, through which opening the rellector 16 is slid in. In this case it is also advantageous to cement the rellector to the lower wall of the body 17.

Warping of the wiring 3 as a result of the expansion by heat in working and therefore also contacting the heating plate are prevented by the insulating beads being shaped such that the bottom of the slots 5 are narrower than the diameter of the wiring 3, and consequently short circuits and endangering of the person handling the heater are avoided. The reflectors with their upwards directed concave surfaces guarantee a convenient reflection of the heat of the wiring to the plate to be heated resulting in a considerable increase of the heating effect and a decrease of the cooking period as compared with the hitherto known heaters. The beads are shaped in such a way as to accommodate themselves to any desired curvature of the wiring.

The resistance wiring may be of circular or other form e. g. it may be llattened.

I claim:

l. An electrical heating unit comprising a plate of heat-conducting material having on one face spaced ribs forming a channel between said ribs, an electrical resistance element disposed in said channel and a continuous series of beads of insulating material strung on said element and received in said channel, each of said beads having a longitudinal bore to receive said element and having in one side a slot extending lengthwise of the bead so that the bead is C-shaped in cross section, said slot being narrower than said bore and said heads being strung on said resistance element end-to-end with said slots aligned and facing said plate.

2. An electrical heating unit according to claim l, in which said beads are secured to said ribs so as to be retained in said channel.

3. In an electrical heating unit, a coiled electrical resistance element, a continuous series of beads of insulating material strung on said element, each of said beads having a longitudinal bore to receive said element and having in one side a slot extending lengthwise of the bead so that the bead is C-shaped in cross section, said slot being narrower than said bore and said beads being strung on said element end-to-end with said slots aligned and facing in the direction in which it is desired to direct heat from said resistance element, and a concave relector on the opposite side of said element from said slot and shaped to reect heat from said element toward and through said slot, said ree'ctor comprising a, plurality of separate sections, one carried oy each of said beads.

4..Ar1 electrical heating unit comprising a plate of heat-conducting material having on one face spaced ribs forming a channel between said ribs, an electrical resistance element disposed in said channel, a continuous series of beads of insulating material strung on said element and received in said channel, each of said beads having a longitudinal bore to receive said element and having in one side a slot extending lengthwise of the bead so that the bead is C-shaped in cross section, said slot being narrower than said bore and said beads being strung on said resistance element end-to-end with said slots aligned and facing said plate, and a concave reector on the opposite side of said element from said slots and shaped to reect heat from said element through said slots'towardsaid plate.

5. An electrical heating unit according to claim 4, in which said reflector is backed by heat-insulating material.

References Cited in the le of this patent UNITED STATES PATENTS 819,654 VHeath -May 1, 1906 1,291,423 Crary Jan, 14, 1919 1,406,360 Forshee Feb. 14, 1922 1,715,690 Ziola June 4, 1929 1,835,602 Kercher et al Dec. 8, 1931 2,121,283 Challet June 21, 1938 2,489,190 Lelong Nov. 22, 1949 2,498,442 Morey Feb. 21, 1950 2,549,944 Steiner Apr. 24, 1951 

